The cleaning and sterilization of swimming pools is currently accomplished using any one or more of mechanisms such as salt water chlorination or chlorine addition.
Chlorine is a strong bleach. It is dangerous. Side effects of its use can include red, irritated eyes, dried and brittle hair, and swimmers ear, bleached out swimsuits, dry itchy skin, and a clinging odor of chlorine.
Chlorine absorbs through the skin. Studies have linked chlorine with cancer, high blood pressure, anemia, heart disease, hardening of the arteries, senility, stroke and other degenerative diseases. Scientists have reported that chlorine is a leading cause for the erosion of the earth's ozone layer. It only occurs naturally safely wrapped up in compounds which are relatively unreactive.
Some of the problems associated with using chlorine have been discussed in literature sources such as:    1. Aggazzotti, G., Fantuzzi, G., Righi, E., & Predieri, G. (1998). Blood and breath analyses as biological indicators of exposure to trihalomethanes in indoor swimming pools. Science of the Total Environment, 217, 155-163.    2. Lindstrom, A. B., Pleil, J. D., & Berkoff, D. C. (1997). Alveolar breath sampling and analysis to assess trihalomethane exposures during competitive swimming training. Environmental Health Perspectives, 105(6), 636-642. And    3. Drobnic, F., Freixa, A., Casan, P., Sanchis, J., & Guardino, X. (1996). Assessment of chlorine exposure in swimmers during training. Medicine and Science in Sports and Exercise, 28(2), 271-274.
Salt water chlorination is a particularly popular technique in which salt (pure, natural rock salt) is dissolved in pool water and then subjected to simple electrolysis. This electrolysis usually takes place in an in-line electrolysis cell. The chloride portion of the salt (sodium chloride) is transformed during the electrolysis into an effective sanitizer, hypochlorous acid, (HOCl) which has the ability to oxidize (kill) bacteria, virus, algae and other such radicals which would otherwise flourish in the water. This process is reversible, so does not consume the salt, which is simply used over and over again.
HOCl is the same effective sanitizer as would result if ‘pool chlorine’ was added to the water—is utilised to minimise the potentially dangerous chlorine compounds and the obnoxious ‘chemical’ effects commonly associated with manual chlorination—and without the need to handle chemicals. It does not always achieve this aim.
Oxidation normally takes place in a swimming pool where the water and its associated contaminants are affected by a chemical oxidizer added to the water and used to oxidize oils and body fats. The chemical oxidizers increase the Oxidation Reduction Potential (ORP) of the water in the pool, but they also have their disadvantages. Oxidation Reduction Potential (ORP) is the extent to which a chemical ion exchanges electrons, which lead to electrical charges, during a chemical reaction.
Chemical oxidizers are quite expensive as they must be continually purchased and added to the water. They are also known to have serious health issues regarding toxicity of chemicals & proven toxic side effects of the by-products which include Chloramines, Triharlomethanes and Ozone.
Ionisation is an alternative method used in the sanitizing of swimming pools. Ionization produces copper ions (algaecide) and silver ions (bactericide) into the water flow of the swimming pools. Ionisation is not as effective as a stand-alone treatment for a swimming pool as it requires the addition of an oxidizer in order to be effective. One major benefit of ionization is its residual qualities. The copper and silver ions are not affected by heat or ultraviolet light and will remain in the water effective as a sanitizer for weeks after the system is shut down. Unlike chlorine and ozone, the copper/silver ions are not considered toxic at the levels required to sanitize the water.
The modern ioniser consists of two parts; the electrode assembly consisting of two (or multiples of two) bars of metal usually made of an alloy of copper and silver and the electronic control unit. The electrodes are usually installed in the swimming pool's filtration system. The control unit supplies the necessary extra low voltage across the electrodes. The resultant current produces positively charged ions of the constituent metals which are carried into the pool and become part of the chemistry of the pool water.
Silver ions act as a disinfectant and copper ions act as an algaecide. Although these ions kill algae and bacteria and provide a measurable residual quality, they do require an oxidiser to be present for the oxidation of organic wastes. Most manufacturers recommend the use of chlorine, but non-chlorine chemical oxidisers are also available.
Ozone is one of the most effective disinfectants and oxidisers available and once introduced into the water it starts to work immediately, killing bacteria and oxidising organic waste. As ozone is not highly soluble in water, the ozone must be injected into the water by either a compressor or venturi system.
However, as ozone is also toxic, all traces must be used or removed prior to a person using the pool. As there can be no residual of ozone when the pool is used, some other form of residual sanitiser like chlorine or bromine must also be used in order to provide continuous protection when the ozone generator is turned off.
Ultrasonics can also be used to clean surfaces remove existing scale, prevent scale formation and assist in sanitizing the water in the swimming pool by helping to break down the protective shell of most common parasitic organisms. Ultrasonic cleaning is a result of sound waves introduced into the water by means of a series of coils wrapped around a pipe that is part of the filtration circuit. The sound travels through the pipe carrying the water and creates waves of compression and expansion in the liquid. In the compression wave, the molecules of the fluid are compressed together tightly. Conversely, in the expansion wave, the molecules are forced apart, creating microscopic bubbles. The bubbles only exist for a split second and contain a partial vacuum while they exist.
As the pressure of the bubbles increases, the fluid around the bubble rushes in, collapsing the bubbles rapidly. When this occurs, a jet of liquid is created that may travel very quickly. They rise in temperature to as high as 5000 degrees Celsius. This extreme temperature, combined with the velocity of the liquid jet provides an intense cleaning action in a minute area. Due to the very short duration of the bubble expansion and collapse cycle, the liquid surrounding the bubble quickly absorbs the heat and the area cools quickly.
Potential problems in ultrasonic cleaning exist if the set point of any one or more of cleaning cycle time, temperature, chemistry, proximity to the transducer, ultrasonic output frequency, watts per liter or the volume of the liquid being cleaned is not correctly adjusted.
Traditional ultrasound technology is currently applied to the processing of low volumes and flow rates, typically in the range of 60-100 gallons per minute.
Each of the above systems has advantages and disadvantages. The inventors of the present invention have found that ionization on its own has an excellent residual but requires addition of an oxidizer, generally requiring the addition of chemicals or ozonation to prevent the build-up of debris on pool surfaces and the oxidization of oils and body fats.
Ultrasonics on its own will prevent the build-up of scale on pool surfaces and fitting and the reduction of parasitic growth.
Electronic Oxidization on its own would have to operate constantly to maintain the residual disinfection in the body of the pool water making it uneconomical in the domestic a commercial environment/
The inventors of the present invention found that the three processes working together complement each other and combine to be an excellent system in providing the required sanitizing processes without the addition of chemicals or ozone to achieve oxidization.
It will be clearly understood that, if a prior art publication is referred to herein; this reference does not constitute an admission that the publication forms part of the common general knowledge in the art in Australia or in any other country.